1. Field of the Invention
Aspects of the present invention relate to a hydrocarbon reforming catalyst, a method of preparing the same, and a fuel processor including the same. More particularly, aspects of the present invention relate to a hydrocarbon reforming catalyst including an active catalyst component impregnated in an oxide carrier and a thermally conductive material having higher thermal conductivity than that of the oxide carrier, a method of preparing the same, and a fuel processor including the same.
2. Description of the Related Art
Fuel cells are electricity generation systems that directly convert the chemical energy of oxygen, and hydrogen in hydrocarbons, to electrical energy. Examples of hydrocarbons include methanol, ethanol, and natural gas.
Fuel cell systems include a fuel cell stack, a fuel processor (FP), a fuel tank, and a fuel pump. The fuel cell stack is the main body of a fuel cell, and comprises a plurality (several to several tens) of unit cells that each includes a membrane electrode assembly (MEA) and a separator (or bipolar plate).
The fuel pump supplies fuel in the fuel tank to the fuel processor. The fuel processor produces hydrogen by reforming and purifying the supplied fuel and further supplies the produced hydrogen to the fuel cell stack. The fuel cell stack receives the hydrogen and generates electrical energy from an electrochemical reaction of the hydrogen with oxygen.
The fuel processor includes a reformer. The reformer of the fuel processor reforms hydrocarbon fuel using a reforming catalyst. However, because the hydrocarbon fuel contains a sulfur compound, the reforming catalyst can be easily poisoned by the sulfur compound. Accordingly, it is necessary to remove the sulfur compound prior to reforming the hydrocarbon fuel. Thus, hydrocarbon fuel is subjected to desulfurization prior to a reforming process as shown in FIG. 1.
FIG. 1 is a schematic flowchart illustrating a method of processing fuel in a fuel processor of a related art fuel cell system. As shown in FIG. 1, a desulfurization process, a reforming process, and a carbon monoxide (CO) removing process are performed in the fuel processor. The CO removing process includes a high temperature shift reaction, a low temperature shift reaction, and a preferential CO oxidation (PROX) reaction.
During the reforming process, for an example of the natural gas steam reforming, the reformer reforms a hydrocarbon fuel using a reforming catalyst with an addition of steam (H2O) to the hydrocarbon fuel to produce hydrogen through Reaction 1:CH4+H2O→CO+3H2  [Reaction 1]
The Reaction 1 occurring during the reforming process of the hydrocarbon fuel is an endothermic process that requires a great amount of heat. Accordingly, the reforming process requires a supply of heat, and thus is performed by using a catalyst at a high temperature. To obtain a high hydrogen production rate, a catalyst having excellent catalytic activity and high thermal conductivity is needed to instantly transfer heat required for the reaction.
Research on related art hydrocarbon reforming catalysts is focused on high catalytic activity. Generally, excellent catalytic activity is obtained by using a catalyst with precious metal active component distributed on a carrier formed of an oxide such as alumina, silica, or the like. However, for a better hydrocarbon conversion rate, a hydrocarbon reforming catalyst having both a high catalytic activity and a high thermal conductivity is required.